Antibiotics and Snake Bites

June, 1996

Dear Dr. Silverio,

Since we can no longer purchase Combiotic, I would like to know what you recommend in place of it. I have had two suggested: Liquamycin La-zoo and Penicillin G Procaine. The main things 1 use this for is Kennel Cough and infection after snake bite.

Thank you, Charles Weathers Meridian, MS

Combiotic was the name of an injectable medication which contained a combination of two antibiotics, Penicillin and digydrostreptomycin, to achieve a broad spectrum of antibacterial activity. FDA requirements for re-licensing existing combination medicines had become more stringent, demanding that drug companies finance new studies to prove effectiveness of all combination drugs or take the produce off the market. Combiotic has been unavailable for a number of years.

Antibiotic treatment is never a guaranteed cure for any infection, but certain disease syndromes, such as Kennel Cough, are frequently associated with the same or similar bacterial infections each time they occur. When a dog has Kennel Cough, or Infectious Tracheobromchitis, his airways are usually infected with one of several viruses (Parainfluenza Virus and Canine Adenoviruses are the most common). There is always secondary bacterial infection, also (Bordetella is the most common one). A third organism, Mycoplasma, is also frequently present. The ingredient in Liquamycin, oxytetracyxline, isa very good choice for treating infection with either Bordetella or Mycoplasma or both.

In regard to snake bites in dogs, the problems that need to be considered are bacterial infection from the bite itself and,
for those species that produce venom, we must treat the poisoning (or envenomization), which can be life-threatening.

Many types of bacteria are known to live in the mouth of healthy snakes and can lead to infection of the bite wound inflicted on a person or a dog. Many of these are anaerobes, bacteria that live in environments with little or no oxygen, and tend to cause stubborn and persistent infections. Penicillin is a good antibiotic to use against anaerobic infections, but has a narrow spectrum of activity against the more common aerobic bacterial infections, and is probably not the best choice of antibiotic to treat bite wounds. Broad spectrum antibiotics, such as enrofloxacin, may be more appropriate and can be used in combination with penicillin.

The effects of envenomization may require more than antibiotics and are best treated at a veterinary hospital. The signs can range from discomfort and swelling at the site of the bite wound to severe, life-threatening, systemic signs. The severity depends on many factors. The size of the victim, the site of the bite and the time elapsed before appropriate treatment is begun, are all important. Too much physical activity after the bite occurs can also increase the uptake of venom. The time of year as well as the age and aggressiveness of the snake are also factors. The most important factor may be the species of the snake, however, geographic location needs to be considered. For example, Mojave rattlesnake envenomization in some areas, such as Southern California, can cause rapid death from respiratory paralysis or severe muscle damage and kidney failure. In other areas, Mojave rattlesnake bite may be more benign, causing only low blood pressure and drooping eyelids.

In general, the toxic ingredients in venom can cause disease through heart dysfunction, blood clotting disorders, neuralgic
disease or severe muscle necrosis. The muscle damage leads to a buildup of the protein, myoglobin which can, in turn, lead to kidney failure.

The bites of Copperheads usually cause minimal signs. Western Diamondbacks are the most likely to cause bleeding problems and the resultant anemia. Pit vipers cause mostly localized signs (pain and swelling). Elapids, such as Coral Snakes, frequently cause salivation, vomiting, apprehension and then convulsions and respiratory paralysis.

The necessary treatment, then, depends on the signs. At the veterinarian’s office, samples of blood and urine may be collected and the bite wound may be cultured and treated. Possible treatments include intravenous fluids and broad spectrum antibiotics. Cortisone administration is controversial but is usually attempted. Antivenin administration is an important part of therapy but has the potential to cause severe allergic reactions.

The best advice I can give regarding snake bites is to know what venomous species of snakes exist in the area where your dogs will be hunting. If a bite occurs and you are unable to identify the species involved, whenever there is a chance of envenomization, you should seek veterinary attention as soon as possible.

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